Amount Of Soil Carbon Research Articles

Stronger increase of methane emissions from coastal wetlands by non‐native Spartina alterniflora than non‐native Phragmites australis

Societal Impact StatementThe invasive species S. alterniflora and P. australis are fast growing coastal wetland plants sequestering large amounts of carbon in the soil and protect coastlines against erosion and storm surges. In this global analysis, we found that Spartina and Phragmites increase methane but not nitrous oxide emissions, with Phragmites having a lesser effect. The impact of the invasive species on emissions differed greatly among different types of native plant groups, providing valuable information to managers and policymakers during coastal wetland planning and restoration efforts. Further, our estimated net emissions per wetland plant group facilitate regional and national blue carbon estimates.Summary Globally, Spartina alterniflora and Phragmites australis are among the most pervasive invasive plants in coastal wetland ecosystems. Both species sequester large amounts of atmospheric carbon dioxide (CO2) and biogenic carbon in soils but also support production and emission of methane (CH4). In this study, we investigated the magnitude of their net greenhouse gas (GHG) release from invaded and non‐invaded habitats. We conducted a meta‐analysis of GHG fluxes associated with these two species and related soil carbon content and plant biomass in invaded coastal wetlands. Our results show that both invasive species increase CH4 fluxes compared to uninvaded coastal wetlands, but they do not significantly affect CO2 and N2O fluxes. The magnitude of emissions from Spartina and Phragmites differs among native habitats. GHG fluxes, soil carbon and plant biomass of Spartina‐invaded habitats were highest compared to uninvaded mudflats and succulent forb‐dominated wetlands, while being lower compared to uninvaded mangroves (except for CH4). This meta‐analysis highlights the important role of individual plant traits as drivers of change by invasive species on plant‐mediated carbon cycles.

Estimated mangrove carbon stocks and fluxes to inform MRV for REDD+ using a process-based model

Mangrove forests are important due to their strong capability for carbon storage, especially in soils. Understanding carbon dynamics in these forests is fundamental to estimate their roles in carbon storage and mitigating climate change. This study used a process-based model, MCAT-DNDC, to assess mangrove carbon sequestration and fluxes at a 30-m spatial resolution in three African countries, Gabon, Mozambique and Tanzania. The simulated above- and below-ground biomass at inventory plots in each country was approximate to actual observations with mean errors <5% for aboveground biomass and <8% for belowground biomass, indicating that the MCAT-DNDC model can be a useful tool for assessing mangrove carbon storage and fluxes. The results from assessing mangrove carbon storage and fluxes for the three countries showed that the mangroves in these countries are large carbon pools, they export large amounts of dissolved and particulate carbon components to riverine and oceanic ecosystems, and they bury a large amount of carbon in soils. However, soil-borne greenhouse gases CO2, CH4 and N2O fluxes from mangrove forest lands were low. There were large differences in all mangrove carbon components among the mangroves in the three countries, indicating that regional or global mangrove carbon stocks estimated using a process-based model may be better than the extrapolations using limited inventories.

Release of glucose from dissolved and mineral‐bound organic matter by enzymatic hydrolysis

AbstractSorption of dissolved organic matter (DOM) by poorly crystalline minerals during their formation may protect large amounts of carbon in soils from mineralization. We investigated the bioavailability of carbohydrates in DOM and after co‐precipitation with short‐range ordered aluminosilicates. Carbohydrates originated from soil solutions collected in situ at two depths of a Dystric Cambisol, and from litter extracts. Quantification of substrate‐specific degradability was achieved by the addition of β‐glucosidase at an optimal concentration and subsequent determination of glucose release. Depending on DOM composition, 0.6–41.4 mg g−1 C−1 of glucose was enzymatically released from dissolved carbohydrates. Co‐precipitated carbohydrates were partially accessible, resulting in a glucose release of 0.7–5.2 mg g−1 C−1. Restricted enzymatic depolymerization due to co‐precipitation may contribute to accumulation of easily degradable substrates in soils.

InVEST Carbon 모형을 활용한 수도권정비계획법 상 권역 별 토지이용변화와 탄소저장량 변화 분석

Carbon storage is a critical ecosystem service function and has recently been affected by land use change and urbanization. In this study, the change in carbon storage was estimated by analyzing changes in land use by region under the Seoul Metropolitan Area Readjustment Planning Act and utilizing the InVEST Carbon model. Based on this analysis of land use change, the Overconcentration Control Region (OCR) showed low urban growth rates and low deforestation rates; the Growth Management Region (GMR) showed high urban growth rates and high deforestation rates; and the Nature Preservation Region (NPR) showed high urban growth rates and low deforestation rates. The smallest loss in carbon storage occurred in the NPR, while significant losses were observed in OCR and GMR. According to our analysis considering carbon sink, the amounts of above and below biomass increased slightly, but the amounts of soil carbon and dead organic matter significantly decreased. This study highlighted land use and carbon management in two ways. First, the region

Valuing carbon capture in agricultural production: examples from Sweden

Agriculture is regarded as a net emitter of greenhouse gases (GHG), but sequesters huge amounts of carbon in soils, bioenergy substrates, and food products. The global accounting system for climate impact based on life cycle assessment (LCA) methodology only takes account of costs (emissions), and not income (carbon and energy binding), leading to the conclusion that agricultural activities should decrease to mitigate climate change. This study considered an alternative accounting system, carbon capture LCA (CC-LCA), that allocates value to carbon sequestration in agricultural products. For two case farms in Sweden (arable, dairy), CC-LCA was applied to (1) calculate the carbon footprint of agricultural production by accounting for net GHG emissions from farm production, rather than gross emissions only, and (2) assess the net impact of mineral nitrogen fertilizer. For the arable farm, CC-LCA revealed net carbon binding of 4 Mg CO2-eq per hectare (net sink), compared with emissions of 1.6 Mg CO2-eq per hectare in LCA. For the dairy farm, both approaches showed emissions of about 10 Mg CO2-eq per dairy cow, mainly due to ruminant digestion. The results also showed that mineral nitrogen fertilizer effectively contributed to carbon sequestration. Compared with an unfertilized wheat crop, a fertilizer dose of 200 kg N ha−1 was estimated to bind about eight-fold more GHG and energy in grain than was released or used during fertilizer production and crop cultivation. Thus, we argue that future strategies aiming for climate-friendly products and practices must acknowledge that agriculture sequesters carbon in products.

From savanna to suburb: Effects of 160 years of landscape change on carbon storage in Silicon Valley, California

Landscape changes such as urbanization can dramatically affect the provision of ecosystem services such as carbon storage. However, while cities have been shown to store substantial amounts of carbon in soils and vegetation, we have little information from long-term studies about how contemporary carbon storage in urban areas compares to carbon storage in the natural ecosystems that characterized these landscapes prior to urbanization. We used historical archival sources and land-cover data to quantify and map historical tree carbon storage in the now-urban Santa Clara Valley, California, USA prior to substantial Euro-American modification (ca. 1850) and to analyze change in the amount and distribution of carbon storage over the past ca. 160 years. We estimate that total tree carbon storage in the study area was ~784,000 to 2.2 million Mg (13.6–38.1 Mg C/ha) when the region was characterized by oak savanna and woodland habitats, compared to ~895,000 Mg C (15.5 Mg C/ha) today. This represents a non-significant gain of 14% to a significant loss of 60% depending on scenario. We also demonstrate changes in the spatial distribution of carbon on the landscape, as losses in carbon storage in areas of former oak woodland were partially offset by gains in carbon storage in historical habitat types that historically had few or no trees. This challenges the hypothesis that aboveground carbon storage increases with urbanization in Mediterranean-climate ecosystems due to irrigation and tree planting. Our study demonstrates the utility of using pre-1900s historical sources to reconstruct changes in ecosystem services such as carbon storage over century time scales.

Old Arctic carbon stability

The Arctic stores vast amounts of soil carbon, much of which is likely to be lost to the atmosphere as the climate warms. A clever new analytical approach suggests that even carbon that has been stored for hundreds to thousands of years is vulnerable to warming.

Functional diversity of ectomycorrhizal fungal communities along a peatland–forest gradient

Peatlands are valuable wetland ecosystems that are widespread in boreal forest regions. In addition to harboring numerous uniquely adapted species, they play a major role in global climate regulation due to their ability to sequester large amounts of carbon in soil. Despite their significance, however, many aspects of peatland ecology remain largely unknown. Our study aimed to deepen the understanding of one such aspect, namely peatland ectomycorrhizal (ECM) fungal communities. The structure of belowground ECM fungal communities of Scots pine along a peatland – forest ecotone in the Lithuanian Čepkeliai peatland was examined by molecular identification of ectomycorrhizae collected at the study sites. Additionally, the ectomycorrhizae functionality, as expressed by exploration types, was assessed. The results revealed significant differences in the taxonomic composition of ECM fungal communities along the gradient. Moving from peatland to forest, a gradual increase in ECM fungal taxonomic richness was observed. As the soil water content increases, the medium and long distance exploration types of ectomycorrhizae became more prevalent and dominated on the peatland site. To our knowledge, this study is the first to document ECM fungal communities of Scots pine in peatland conditions and in European peatlands more broadly.

Carbon outwelling and emissions from two contrasting mangrove creeks during the monsoon storm season in Palau, Micronesia

Mangroves sequester large amounts of carbon in soils but limited information is available on carbon losses from tropical mangrove systems. Here we quantify carbon outwelling, CO2 emissions and pore-water exchange rates from two nearby (∼2 km apart) tropical mangrove creeks located in different geomorphic settings on the island of Palau, Micronesia during the monsoon storm season. On average, POC and pCO2 were >100% higher and DOC, DIC and TA were 62%, 25%, 16% higher, respectively, from Creek 1 (located within a semi-enclosed bay) than from Creek 2 (located along the coast adjacent to fringing reefs). Both creeks were net exporters of DIC, DOC, POC, TA and emitters of CO2. However, outwelling rates of POC, DIC and DOC and CO2 emissions were 27-fold, 8-fold, 4-fold and 3-fold higher at Creek 1. DIC outwelling (37%) and CO2 emissions (39%) were the major terms contributing to total carbon losses at Creek 1, whilst CO2 emission (61%) was the major contributor at Creek 2. Monsoon storms appeared to explain the organic carbon dynamics whilst tidal pumping appears to drive the inorganic carbon dynamics at both creeks. Our data demonstrates the considerable heterogeneity of mangroves creeks that are in close proximity and subject to similar weather conditions but in differing geomorphological settings.

Contradicciones socioambientales en los procesos de mitigación, asociados al ciclo del carbono en sistemas agroforestales

En distintas regiones del mundo, la agroforestería ha contribuido a mejorar los sistemas de producción agrícola, la soberanía alimentaria y la conservación de la biodiversidad, así como a mitigar y adaptarse a los efectos del cambio climático. El maíz, el café y la ganadería bovina, son actividades agropecuarias esenciales en los estados del sur de México. En Chiapas existen diversas experiencias agroforestales de mitigación que sobresalen por su multifuncionalidad: producen alimentos y bienes forestales y, al mismo tiempo, mantienen funciones socioambientales. Los proyectos de mitigación presentan barreras y contradicciones socioambientales para la implementación y continuidad, aunque han mostrado su importancia en la mitigación de gases efecto invernadero. El objetivo de este trabajo es discutir las contradicciones (trade-offs) que se presentan en proyectos agroforestales para mitigación de gases efecto invernadero. En los sistemas analizados se encontraron importantes cantidades de carbono en la materia orgánica del suelo, biomasa viva y muerta. Desde la perspectiva de la producción de alimentos y madera, así como de la conservación de especies y funciones ecosistémicas, los sistemas agroforestales manejados en pequeña escala son estratégicos. No obstante, se observaron limitaciones desde la perspectiva de los productores en el terreno de los beneficios económicos y necesidades de organización para el mercado, los requisitos, la capacitación, la competencia por uso del suelo y la inversión del trabajo. Las ventajas y desventajas son elementos importantes a ser tomados en cuenta en el diseño de sistemas agroforestales y programas de servicios ecosistémicos. En la medida que se entiendan estos procesos, habrá mayor posibilidad de éxito con beneficios locales y globales.

The Effects on Greenhouse Gas Emissions of Ecological Intensification of Meat Production with Rainfed Sown Biodiverse Pastures

Feed production is an important contributor to the environmental impacts caused by livestock production. In Portugal, non-dairy cattle are commonly fed with a mixture of grazing and forages/concentrate feed. Sown biodiverse permanent pastures rich in legumes (SBP) were introduced to provide quality animal feed and offset concentrate consumption. SBP also sequester large amounts of carbon in soils. Here, we used a comparative life cycle assessment approach to test the substitution of concentrate through installation of high-yield SBP. Using field data for the Alentejo region in Portugal, we compare the global warming potential of a baseline scenario where cattle is fed in low-yield, semi-natural pastures supplemented with feeds that vary in the ratio of silage to concentrate, and a second scenario where the feed is substituted with high-yield SBP. Although SBP use more fertilizers and machinery, this replacement avoids the emission of about 3 t CO2eq/ha even after SBP stop sequestering carbon. Using crude fiber to establish the equivalence between scenarios leads to higher avoided impact, owing to the fact that the fiber content of SBP is also higher. SBP can avoid 25% emissions from beef production per kg of live animal weight.

Reducing greenhouse gas emissions in agriculture without compromising food security?

To keep global warming possibly below 1.5 °C and mitigate adverse effects of climate change, agriculture, like all other sectors, will have to contribute to efforts in achieving net negative emissions by the end of the century. Cost-efficient distribution of mitigation across regions and economic sectors is typically calculated using a global uniform carbon price in climate stabilization scenarios. However, in reality such a carbon price would substantially affect food availability. Here, we assess the implications of climate change mitigation in the land use sector for agricultural production and food security using an integrated partial equilibrium modelling framework and explore ways of relaxing the competition between mitigation in agriculture and food availability. Using a scenario that limits global warming cost-efficiently across sectors to 1.5 °C, results indicate global food calorie losses ranging from 110–285 kcal per capita per day in 2050 depending on the applied demand elasticities. This could translate into a rise in undernourishment of 80–300 million people in 2050. Less ambitious greenhouse gas (GHG) mitigation in the land use sector reduces the associated food security impact significantly, however the 1.5 °C target would not be achieved without additional reductions outside the land use sector. Efficiency of GHG mitigation will also depend on the level of participation globally. Our results show that if non-Annex-I countries decide not to contribute to mitigation action while other parties pursue their mitigation efforts to reach the global climate target, food security impacts in these non-Annex-I countries will be higher than if they participate in a global agreement, as inefficient mitigation increases agricultural production costs and therefore food prices. Land-rich countries with a high proportion of emissions from land use change, such as Brazil, could reduce emissions with only a marginal effect on food availability. In contrast, agricultural mitigation in high population (density) countries, such as China and India, would lead to substantial food calorie loss without a major contribution to global GHG mitigation. Increasing soil carbon sequestration on agricultural land would allow reducing the implied calorie loss by 65% when sticking to the initially estimated land use mitigation requirements, thereby limiting the impact on undernourishment to 20–75 million people, and storing significant amounts of carbon in soils.

Climatically driven change in soil carbon across a basalt landscape is restricted to non-agricultural land use systems

Soils represent a significant component of the global terrestrial carbon cycle. Historical soil carbon depletion resulting from soil and land management offers an opportunity to store additional carbon to offset greenhouse gas emissions as part of our international response to climate change. However, our ability to reliably measure, estimate and predict soil carbon storage is hindered by a range of sources of variability, not least of which is change through time. In the present study, we assessed temporal changes in soil organic carbon (SOC) and its component fractions in response to climate alone and in the absence of land use change at any given site by examining a series of soil monitoring sites across a basalt landscape in north-west New South Wales under a range of land use types over a 3-year period (March–April 2008 and March–April 2011), where a significant rainfall event had occurred in the intervening time (2010). Across the dataset, woodland soils contained the largest carbon concentration (SOC%) and total organic carbon stock (TOCs) compared with other non-wooded land use systems, which themselves were statistically similar. However, larger carbon quantities were restricted largely to the surface (0–10cm) soil layers. Between 2008 and 2011, significant increases in SOC% and TOCs were detected, but again these were restricted to the woodland sites. No change in particulate organic carbon (POC) was detected between the two sampling times, but both humic organic carbon (HOC) and resistant organic carbon (ROC) increased in woodland soils between the two sampling times. Increased HOC we attribute to microbial processing of soil carbon following the 2010–11 rainfall event. However, we suggest that increased ROC results from limitations in mid-infrared calibration datasets and estimations. We conclude that the quantity of soil carbon and its component fractions is, indeed, driven by climatic factors, but that these effects are moderated by aboveground land use and SOC inputs.

Response of soil nutrient content, organic matter characteristics and growth of pine and spruce seedlings to logging residues

The aim of this study was to determine the effects of different amounts of logging residues on soil properties and growth of Scots pine and Norway spruce seedlings 10years after clear-felling. The field experiments consisted of two Scots pine and four Norway spruce experiments. The treatments, on three replicate 8m∗8m plots in all field experiments, were whole-tree harvesting, i.e. harvesting all the above-ground biomass with no logging residue left on the site (R0), stem-only harvesting, leaving logging residues on the site (R1), and stem-only harvesting with double the amount of logging residues left on the site (R2). In the R1 treatment the amount of logging residue in the spruce stands was 39–54Mgha−1 dry mass and in the pine stands, 11–18Mgha−1 dry mass. Over all sites, logging residues had no consistent effects on seedling growth, amounts of soil carbon and nutrients or organic matter characteristics. In some spruce experiments, however, logging residues increased the average diameter, height and height growth (last three years), as well as the number of seedlings, stem volume and biomass. In pine experiments, logging residues had no effect on tree or stand characteristics. In one pine experiment the amounts of exchangeable base cations increased, and there were also changes in the quality of organic matter: the C/N ratio decreased, and NH4–N, microbial biomass N and C mineralization increased due to residues. In the spruce experiments and the other pine experiment, the effect of logging residues on the soil properties measured was slight. Logging residues did not affect NO3–N concentrations or rates of net nitrification, which in most soils were both negligible. Seedling height and height growth correlated strongly and positively with net N mineralization and its ratio to microbial biomass N. All in all, logging residues improved tree and stand characteristics generally in spruce stands, but the effects on soil properties and processes, if any, occurred mostly in one pine stand. This poor correspondence may point to other changes brought on by the logging residues, such as changes in physical environment or decreased competition with ground vegetation, being more important for seedling growth than nutrient status was.

Soil carbon accrual in particle-size fractions under Miscanthus x. giganteus cultivation

The energy crop Miscanthus x. giganteus is a deep rooting perennial rhizomatous C4 grass with great biomass production, even under temperate German climate conditions. Accordingly we hypothesized that this crop may accumulate great amounts of carbon in soil, particularly in deeper soil layers. We sampled several former C3-derived arable fields that had been cropped with Miscanthus for 0–19 years. We were able to trace the origin and turnover of soil organic C (SOC) on the basis of natural 13C/12C abundance measurements. The analysis was performed on bulk soil samples and on particle-size fractions that are known to comprise SOC of different availability for decay. Miscanthus-derived C accumulated at a rate of 1800 kg ha−1 y−1 down to a soil depth of 100 cm. Only about 50% of this C accrual occurred in the surface soil (0–10 cm). The C accumulation differed among size fractions. Miscanthus-derived C in the coarse-POM fraction increased rapidly during the first years of Miscanthus cultivation until a steady state was reached after approximately seven years. The stocks of Miscanthus-derived C associated with the clay fraction increased at a rate of 230 kg ha−1 y−1 in 0–5 cm, 45 kg ha−1 y−1 in 20–30 cm and 38 kg ha−1 y−1 in 50–75 cm. The C accumulation rate decreased with increasing soil depth. In particular, Miscanthus-derived C associated with the clay fraction led to increasing SOC stocks, even below the former Ap; that is, below a depth that would respond sensitively to a future land use change.

中国东部南北样带典型针叶林土壤酶活性分布格局研究

PDF HTML阅读 XML下载 导出引用 引用提醒 中国东部南北样带典型针叶林土壤酶活性分布格局 DOI: 10.5846/stxb201309272377 作者: 作者单位: 中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心,中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心,中国科学院大学,中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心,中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室CERN综合研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(31070435,31290222,31290221);国家重点基础研究发展计划项目(2012CB417103,2010CB833502);中国科学院地理科学与资源研究所"秉维"优秀青年人才基金(2011RC202);中国科学院战略性先导科技专项(XDA05050600) Pattern of enzyme activities of typical coniferous forest soils along the North-South Transect of Eastern China Author: Affiliation: Institute of Geographic Sciences and Natural Resources Research,,University of Chinese Academy of Sciences,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选取中国东部南北样带不同气候区(寒温带、温带和亚热带)的针叶林作为研究对象,分析了多酚氧化酶、过氧化物酶、几丁质酶以及β-葡萄糖苷酶活性的变化。结果表明,土壤溶解性有机碳(DOC)、微生物生物量碳(MBC)、微生物生物量氮(MBN)含量从北到南依次减小,寒温带显著高于亚热带;土壤pH值在3个气候区差异显著,温带最高,亚热带最低。分解木质素的多酚氧化酶和过氧化物酶活性不存在显著性差异;而与氮循环密切相关的几丁质酶活性表现为温带显著高于寒温带和亚热带;与碳循环密切的β-葡萄糖苷酶活性在温带最高,并显著高于亚热带地区。逐步回归分析表明,土壤MBN与pH值影响土壤几丁质酶活性,而土壤β-葡萄糖苷酶活性主要受pH的控制。研究认为,在中国东部南北样带针叶林中,土壤几丁质酶和β-葡萄糖苷酶活性存在显著性差异,而pH与MBN可能是影响土壤酶活性的主要因素。 Abstract:Soil organic carbon (SOC) is the largest terrestrial pool of carbon, and the amount of carbon in soils represents about two thirds of total ecosystem. Therefore, any change in the size and turnover rate of SOC pools will potentially alter the atmospheric CO2 concentration and the subsequent global climate. Soil enzymes are involved in a series of catalyzing reactions and play pivotal roles in litter and soil organic matter decomposition as well as nutrient cycling in terrestrial ecosystems. Soil enzyme activity can be used as a proxy for plant and microbial substrate availability, the interference between soil ecosystem and external environment, and microbial community structure and metabolic capabilities. Therefore, the determination of soil enzyme activities is a powerful tool for understanding soil carbon and nitrogen biogeochemical processes and their responses to climate change. Soil enzyme activity has been a frontier of forest ecology research and has been widespread concern. Unfortunately, most of the studies to date have been limited to a single forest biome or a single forest site, and few studies concern the pattern and controlling factors of soil enzyme activity at a terrestrial transect scale. North-South Transect of Eastern China (NSTEC) is the fifteenth standard transect established by International Geosphere-Biosphere Program (IGBP) in 2005 and is mainly driven by heat, followed by precipitation. It covers almost all forest types from boreal forest to tropical rain forest, which provides an ideal tool to investigate the pattern and environmental control of soil enzyme activities in the boreal, temperate and tropical forest biomes. In the past decade, many studies were conducted to measure the main factors affecting the pattern of SOC storage and soil-atmosphere exchange of greenhouse gases in the typical forests along the NSTEC. However, little information is available on the pattern of soil enzyme activities involved in soil carbon and nitrogen cycles and they relate to soil microbial biomass at a large spatial scale. In this study, the typical coniferous forests distributed in the cold-temperate, temperate and subtropical climatic zones were selected along the NSTEC. The activities of polyphenol oxidase, peroxidase, chitinase and β-glucosaccharase, soil dissolved organic carbon (DOC), microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) as well as soil pH in the three coniferous forest soils were measured. The results showed that soil DOC, MBC, and MBN contents tended to decrease from north to south, and they were higher in the cold-temperate forest soils than in the subtropical forest soils. There was a significant difference in the soil pH values among the three coniferous forests, following the order cold-temperate > temperate > subtropical forests. Also, no significant differences were found in the soil polyphenol oxidase and peroxidase activities among the three typical coniferous forests. In contrast, the soil chitinase activity involved in soil nitrogen cycle was significantly higher in the temperate forest than in the cold-temperate and subtropical forests, and the soil β-glucosaccharase activity in the temperate forest was also significantly higher than that of the subtropical forest. Stepwise regression analysis showed that the soil chitinase activity was closely associated with soil MBN content and soil pH value, and the soil β-glucosaccharase activity was significantly and positively related to soil pH value. Our results suggest that soil cellulose- and chitin-degrading enzymes (i.e., chintinase and β-glucosaccharase) sensitively respond to climate zone. Soil MBN content and pH value are the main factors controlling soil enzyme activities of coniferous forests along the NSTEC. 参考文献 相似文献 引证文献

LivestockPlus - The sustainable intensification of forage-based agricultural systems to improve livelihoods and ecosystem services in the tropics

As global demand for livestock products (such as meat, milk and eggs) is expected to double by 2050, necessary increases to future production must be reconciled with negative environmental impacts that livestock cause. This paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the sustainable intensification of mixed crop-forage-livestock-tree systems in the tropics by producing multiple social, economic and environmental benefits. Sustainable intensification not only improves the productivity of tropical forage-based systems but also reduces the ecological footprint of livestock production and generates a diversity of ecosystem services (ES) such as improved soil quality and reduced erosion, sedimentation and greenhouse gas (GHG) emissions. Integrating improved grass and legume forages into mixed production systems (crop-livestock, tree-livestock, crop-tree-livestock) can restore degraded lands and enhance system resilience to drought and waterlogging associated with climate change. When properly managed tropical forages accumulate large amounts of carbon in soil, fix atmospheric nitrogen (legumes), inhibit nitrification in soil and reduce nitrous oxide emissions (grasses), and reduce GHG emissions per unit livestock product.The LivestockPlus concept is defined as the sustainable intensification of forage-based systems, which is based on 3 interrelated intensification processes: genetic intensification - the development and use of superior grass and legume cultivars for increased livestock productivity; ecological intensification - the development and application of improved farm and natural resource management practices; and socio-economic intensification - the improvement of local and national institutions and policies, which enable refinements of technologies and support their enduring use. Increases in livestock productivity will require coordinated efforts to develop supportive government, non-government organization and private sector policies that foster investments and fair market compensation for both the products and ES provided. Effective research-for-development efforts that promote agricultural and environmental benefits of forage-based systems can contribute towards implemention of LivestockPlus across a variety of geographic, political and socio-economic contexts.Keywords: Eco-efficiency, environmental benefits, livestock and environment, mixed farming, pastures, smallholders.DOI: 10.17138/TGFT(3)59-82

SOIL ORGANIC CARBON AS AN INDICATOR OF SOIL QUALITY: A STUDY IN SELECTED TEA PLANTATIONS IN GALLE DISTRICT

Assessment of soil quality in tea lands is important to determine the extent ofdegradation and introduce sustainable land management practices. A study wasundertaken in two stages to assess the suitability of soil organic carbon as a soil qualityindicator in tea lands. Soil samples were taken from 0-15 em tea estates in the GalleDistrict of Sri Lanka. In the first stage, soil samples were depth from selected taken from15 locations under four different field categories viz., under rehabilitation, rehabilitationcompleted, planted tea following rehabilitation and planted tea without rehabilitation.Second stage involved sampling of a tea field under rehabilitation and tea fields ofvarious ages (3, 7 and 11 year old) situated at one location. Soil samples were also takenfrom two forest sites to assess the impact of cultivation on soil organic carbon. Bulkdensity was measured at the field and soil samples were analyzed for total organiccarbon.Results revealed that land management has a significant impact on the quantity of soilcarbon in tea plantations. While rehabilitation process has increased the soil carboncontent, nearly 15% of the added carbon is lost during the initial years after planting tea.Forest soils had a soil organic carbon (in the O-15cmsoil layer) range of 3.39 to 4.42 kgm·2 compared to 3.02 to 3.18 kg m-2 observed in rehabilitated tea lands. The l l-year oldtea field has lost over 40% of its soil organic carbon since rehabilitated and planted withtea. Soil organic carbon can be considered as a robust indicator of soil quality and moreresearch is required to establish critical levels of soil carbon for tea lands in differentstages of the cultivation-rehabilitation cycle

Comparison of the Effects of Tannin and Azadirachtin on Carbon Mineralization in Soils of Quercus coccifera from Eastern Mediterranean Region

In this study, organic matter mineralization was studied in the Quercus coccifera (Kermes oak, Fagaceae) soils mixed with Quercus leaves having high tannin content, Melia azedarach (Neem tree, Meliaceae) leaves and fruits having high azadirachtin content, pure tannin and pure azadirachtin. Carbon mineralization of all samples was determined by the CO2 respiration method over 30 days (28oC and 80% of field capacity). Addition of equal (1x) and half (1/2x) amounts of soil carbon containing leaves of both plants to soils separately increased microbial activity. The increase in microbial activity was higher in 1x leaves added soil compared with 1/2x leaves added soil and was only significant in 1x Melia leaves added soil compared with control (P<0,001). There was no significant difference in carbon mineralization between the 1/2x and 1x Quercus leaves added soils (P≥0.05) whereas the difference between the Melia leaves added (1/2x; 1x) soils was significant (P<0,001). It was determined that the carbon mineralization rates (%) of Quercus soil mixed with pure tannin and pure azadirachtin showed similar behaviours. When amounts of pure tannin and pure azadirachtin were increased, this rates reduced. Based on the results obtained from the findings of this study, it was determined that microorganisms used tannin and azadirachtin as carbon sources and preferred to use azadirachtin rather than tannin.

Effects of logging residue harvest in thinnings on amounts of soil carbon and nutrients in Scots pine and Norway spruce stands

The effects of whole-tree thinning on soil were investigated in 9 Scots pine and 4 Norway spruce experiments in Finland. Three pine experiments had been thinned once, the other experiments twice. Time between thinning and soil sampling varied from 3 to 30 years. Amounts of exchangeable base cations, Ca, K and Mg, seemed to have decreased after whole-tree thinning. The larger the amount of removed logging residues, the greater these decreases tended to be. Changes in base cations in soil due to whole-tree harvest were more expected than were changes in the amounts of nitrogen, because, e.g. potassium and magnesium in logging residues of one thinning corresponded, on average, to 60–70% and to 30–40%, respectively, of the total amounts of nutrients in the organic layer, but nitrogen only to 10%. Overall, in the experiments studied, whole-tree harvest induced only slight changes in soil nutrients. The changes would be even smaller if the present motorised whole-tree harvest, in which logging residues are not totally removed, were compared to the present motorised stem-only harvest, in which logging residues are not distributed evenly over the cutting area.